Various methods have been developed to utilize earthworms to eat decomposing organic matter and excrete a material known as vermicompost or castings. Vermicompost contains a high concentration of beneficial microorganisms that provide a soil amendment beneficial to the growth of plants. Vermicomposting also reduces the amount of household and commercial food waste that would otherwise make its way into landfills where it decomposes anaerobically and creates greenhouse gases and toxic leachate.
The present invention provides a device which significantly reduces the manual labor required to harvest vermicompost compared to other devices currently available.
One type of vermicomposting device currently available in the market is comprised of a number of stacked pans which, with the exception of the bottom pan, are provided with orifices to allow earthworm migration both up and down between the pans. The bottom pan has a solid floor that collects leachate; the uppermost pan is covered. Initially, a single pan is placed above the bottom pan and bedding, worms and organic matter are added. After the pan is filled with decomposing organic matter, another pan is added on top of the filled pan and the process of adding bedding and organic matter is repeated. The worms can travel from one pan to another via the orifices in the floors of the pans and are always able to reach nutritive matter that is added to the uppermost pan. Periodically the upper pans are unstacked and the vermicompost in the lowermost pan is removed; the removed vermicompost may also contain worms, worm eggs, castings and bedding that must be separated from the vermicompost and returned to the bins. Subsequently this pan is provided with fresh bedding and is replaced in the stack as the top pan to which new nutritive matter is added since the earthworms migrate upwardly to feed and breed and downwardly to deposit eggs. Repeated harvesting of the worms from the converted nutrition and bedding is inconvenient and time consuming in that the job is labor intensive. The pans are very heavy and every pan must be removed to harvest the castings from the lowermost pan. Leachate accumulates in the lowest pan, and frequently clogs the spigot typically used to drain the leachate. If the spigot clogs, the heavy bins must be unstacked in order to drain the bottom pan and remove the accumulated leachate that can produce anaerobic conditions in the bin that can adversely affect the worms and create unpleasant odors.
Another approach is a continuous method in which the worms are fed organic matter above a weight bearing grid. A bar, which rests upon the grid, is pulled across the grid to push the finished vermicompost into a lower collection area. A major problem here is the extreme weight of the organic matter pressing down on the grid making it difficult to manually pull the bar across the top of the grid to force vermicompost through the grid.
Consequently, a need remains for an effective, easy to use apparatus and method for converting organic waste matter into a useful substance and enable harvesting of earthworms when desired. It is desirable that such apparatus be compact, operate virtually continuously while maintaining suitable operating conditions, and enable extraction of vermicompost with unstressful manual effort.